This invention relates to joints and connections and more particularly to an improved mitered joint construction and a method for forming such a joint in which the ends of tubular members are joined by both an angled insert and by welding along the inside of the joint.
In manufacturing various products, it is often necessary to form an angled or mitered connection between channels and tubular members. In many applications, such as constructing picture frames from extruded aluminum channel, the connection is not subjected to large forces. One common method for forming 90.degree. connections between mitered ends of picture frame channels is to place an angled insert having two legs disposed 90.degree. apart into the mitered ends of two channels and attaching the insert to the channels with screws. Such a joint construction works quite well for picture frames which support only limited weight. However, this type of joint construction has not been acceptable for many applications subjected to higher forces.
Store display fixtures often are constructed from tubular members having either rectangular or round cross sections. For example, one common display fixture has rectangular uprights connected by rectangular horizontal members. The uprights have a number of vertically spaced slots for receiving shelf support brackets. Mitered joints are often formed between horizontal tubular members and uprights for a neat appearance. Since both the horizontal members and the uprights may be subjected to high forces in store display fixtures, it is necessary to have a strong rigid joint between these members. It is also desirable to have a mitered joint which has a tight look at all times. In the past, the normal method for forming the connections have been to miter or bevel the ends of the horizontal and vertical members and to butt and weld the mitered ends together. For appearance sake, it then was necessary to grind the weld smooth with the surfaces of the tubular members and then to polish the surfaces. Depending upon the finish desired, the tubular members are sometimes painted or plated after they were welded together and the weld is ground smooth. This construction is very strong. However, this joint construction is quite expensive and time consuming to manufacture.